| 摘要 |
The support assembly includes a spring component (5) which via a lever arrangement (6) located around a pivoting axis (6a), activates the wheel (4) to come into contact with the ground. The ladder can thus adopt either a rest position with both supports (2,3) in contact with the ground, or a transport position in which only the wheel (2) is touching the ground. The horizontal rotary axis (4a) is located in the lever arrangement and is parallel to the lever pivoting axis which is carried by a support component (9). When the ladder is moved, the horizontal rotary axis is in a vertical plane (10), between two other such planes (11,12) in which the vertical rotary axis (2a) and the pivoting axis are located. The horizontal rotary axis when the ladder is moved, is nearer the ground than the pivoting axis and an obstacle in front of the wheel tends to pivot the lever arrangement around its axis in the same direction as that produced by the spring component. |
